The invention relates generally to devices for preparing inflated packaging cushions, and more particularly to devices for detecting under-filled packaging cushions.
When articles are packaged in a container or box for shipping, there are usually void spaces in the container. Protective packaging material for articles of different sizes and shapes is commonly used to cushion articles during shipping. Numerous types and forms of packaging material for this purpose have been used, including waste paper, embossed paper, laminated bubble paper, foamed material and plastic beads. These packaging materials do not always provide the cushioning and void fill most effective to protect articles during shipment. These packaging materials can be costly and often require that a significant amount of labor be performed at the packing station.
Thermoplastic cellular cushions containing air have been developed for use as packaging material. Examples of methods of making such cellular cushions are shown in U.S. Pat. Nos. 3,817,803 and 5,340,632. Another example of a device for making cushions is U.S. Pat. No. 5,942,076, which describes a machine that includes sealing sheets of thermoplastic material together to form a tube, introducing air to the tubular material and sealing the ends to make rectangular air-filled cushions of various sizes. The cushion making machine is normally located adjacent a product conveyer. The products are typically placed into boxes or other containers, and packaging cushions from the cushion making machine are used to pack the product.
Various packaging systems have been developed for delivering strings of packaging cushions to one or more packaging stations. U.S. Pat. No. 6,536,183 describes a system for producing and delivering packaging cushions to a point of use in which a continuous string of the cushions is fed into an elongated duct with the string extending longitudinally of the duct. An air flow is established in the duct to convey the string of cushions through the duct to the point of use. In U.S. Pat. No. 6,428,246 there is disclosed a system and method for making, conveying and dispensing a string of packaging cushions to one or more packaging stations. The system includes a pressurized pathway to an elongated hopper located above a plurality of packing stations. The elongated hopper includes air jets that transfer the string of packaging cushions between each jet to a remote end of the hopper. Located at intervals along the length of the hopper are a series of dispensing openings so the cushions may be accessed at each of the packing stations. U.S. patent application Ser. No. 10/780,176 describes a system that uses a series of conveyor belts to deliver and feed strings of packaging cushions to one or more packaging stations.
The above described systems commonly use air or mechanical conveyors to deliver strings of packaging cushions from a cushion forming machine to a plurality of hoppers that are generally located near a packaging station. During packaging operations, an operator may remove a desired amount of packaging cushions from the hopper. Sometimes, the string of cushions delivered to the packaging stations may be deflated or under-filled. Improperly inflated cushions are typically discarded. Delivering improperly inflated cushions to the packaging stations may result in packaging delays and wasted materials. In some cases, packaging production may be delayed until properly inflated packaging cushions can be supplied to the packaging stations. U.S. Pat. No. 6,453,644 describes an air-conveyance system that includes a probe in the form of a whisker trigger for detecting whether a cushion is deflated. The probe interrupts power to the air pillow cushion machine when a single deflated bag is detected. Stopping and starting the cushion machine every time a single deflated packaging cushion is detected may be inefficient, burdensome, and there may be circumstances where it is desirable to stop and restart the machine only if the cushion machine is malfunctioning or an extended string of under-filled cushions is detected.
Thus, there still exists a need for an apparatus and system for detecting under-filled packaging cushions when an extended length of under-filled packaging cushions has been detected or when the cushion machine is malfunctioning.